Reuse reactive dyes

Gatewood, B.M. and Hall, J. 1996. Evaluation of after treatments for reusing reactive dyes. Text. Chem. Color. 28 38 2. 

Hydrolyzed glycosaminoglycans, skin conditioner/ moisturizers, 7 843t Hydrolyzed proteins, in pet foods, 10 855 Hydrolyzed reactive dyes, recovery and reuse of, 9 452, 453... 

The initial reuse research dealt with dyeing of 100% cotton knit underwear fabrics. The approach was to dye 100% cotton with a single reactive dye (low-temperature) in order to determine the initial problems in adapting reuse to reactive dye systems. The analysis of the reactive dyebath was similar to that described for disperse dyes in the general discussion section of this chapter. Since the reactive dye was water soluble, no organic extraction was necessary before analysis. The problems encountered and the solutions derived in this stage were ... 

Figure 1. Dyebath reuse 100% cotton/low-temperature reactive dyes...

Table XXVII. Dyebath Reuse Color Difference Calculations 100% Cotton/One Low-Temperature Reactive Dye...

Dye blends—One of the reactive dyes, a scarlet, was a b1 end, composed of an orange component and a red component. The orange and red components exhausted at different percentages, thus blocking analysis and dye blend adds. The dye manufacturer provided Georgia Tech on a confidential basis with a detailed analysis of the dye blend, allowing reuse analysis and adds of the individual components. 

Savings and Cost/Benefit Analysis. The bench scale experiments were successful Tn overcoming major technical problems while demonstrating that dyebath/auxiliary bath reuse is indeed feasible with reactive dyes on cotton-containing fabrics. In addition, a shortened-cycle dyeing procedure coupled with reuse for cotton/polyester blends was shown to further increase energy, mass, and time savings (Table XXX). 

For the two-step reuse system, the same auxiliaries as utilized in the conventional process system were assumed, and the reactives and disperse dyes of the conventional process were assumed to be replaced on a one-to-one basis by high-energy reactive dyes and base-stable disperse dyes in the reuse procedure. 

Fixation Bath Reuse to Combined Disperse/Reactive Dyeing of Polyester/Cotton Knit Fabric... 

Good lot-to-lot shade correlations were also obtained with reuse of low-temperature reactive dyebaths and fixation baths on 100% cotton, and with reuse of combined high-energy reactive/disperse dyebaths and fixation baths on cotton/polyester knit fabrics. Further computer program development is required, however, before industrial shades can be matched with the reactive dye reuse system. 

Knudsen H. H., Wenzel H, Hansen J. and Cederhohn J. (1999), One year reclamation and reuse of energy and water in reactive dyeing of cotton , 18th IFATCC Congress, Copenhagen, 8-10 September... 

Anon. (1998), Reclamation and Reuse of Process Water from Reactive Dyeing of Cotton , EPA Project Report No. 374 (in Danish, English summary). 

Wenzel H, Knudsen H H, Kristensen G H, Hansen J (1996), Reclamation and reuse of process water from reactive dyeing of cotton . Desalination, 106,195-203. 

Once the dyeing cycle is complete, the CO is gasified to recover the excess dye. Unburdened, the clean CO cycles back into the dyeing vessel for reuse, a manoeuvre that saves energy, water, and the heavy metals that comprise much of the toxic runoff into our planet s polluted waterways, according to DyeCoo. The process isn t without its limitations, however. DyeCoo is currently only able to dye scoured (or prewashed) polyester fabric, although the company notes that it s working on a version that will dye unscoured fabric, as well as reactive dyes for cellulosie textiles made from plants. 

Particularly in the case of dyes with a limited degree of fixation the dyestuff content in the wasted water leads to intensively colored wastewater. As the reactive group of the unfixed dyestuff is hydrolyzed into an inactive form, a reuse is not possible. On the basis of an exhaust dyeing with 5% color depth, a liquor ratio of 1 10, and a degree of dyestuff fixation of 70-80% corresponding to 3.5-4 g/L of dye are fixed on the goods and 1.5-1 g/L of hydrolyzed dyes are released with the dyebath. 

Dvarioniene J., Stasiskiene Z. and Knudsen H. H. (2003), Pilot scale membrane filtration study on reuse of rinsing water after reactive cotton dyeing . Environmental Research, Engineering and Management, No.3, 3-11. 

---